There are many situations in which it is desirable to identify or verify a person's handwriting. It may be desirable to perform such verification in the presence of the person or remotely, for example as a means of controlling access to a computer system from remote locations. There are two basic approaches to such handwriting identification: automatic systems and methods which process data from a reference signature and a specimen signature, and report whether or not the specimen is verified; and comparison systems and methods whereby a stored reference signature and a specimen signature are displayed together to allow the validity of the specimen to be judged by an observer.
In known systems using the first approach, one system generates an analog signal proportional to the tangential pen speed across a surface. The system then internally correlates the signal to a reference signal and reports the degree of correlation. Another system provides automatic verification based on use of a pen having an accelerometer and a pressure sensor, in which the pen acceleration and pressure are used internally as the discriminants. Another system determines the X and Y components of pen speed and uses the magnitude of the differences in the velocity vectors as an internal discriminant.
Systems which provide a display of the specimen signature include a system that determines the axial pressure of the stylus on the writing surface and modulates the intensity of the display with the pressure. This system, however, does not display the speed of the stylus across the writing surface.